CODEWITHSUNDEEP
scalascala-collections
Jeriho
Jeriho

Reputation: 7299

What is the fastest collection for slicing?

I need to execute the following operation:

collection.slice(x, y)
....
collection.slice(x+1, y+1)
...
collection.slice(x+n, y+n)

or

collection.slice(x-n, y-n)

Very often execution of this part of code is expected, so I want to make it as fast as possible. What collection should I choose? (can be immutable).

P.S. on Performance Characteristics page "apply" characteristic is responsible for slicing?

P.P.S looking for articles, manuals dedicated on subject.

Upvotes: 2

Views: 1380

Answers (2)

Daniel C. Sobral
Daniel C. Sobral

Reputation: 297265

Well, Vector has logN performance, though the constant factor may be too heavy depending on your requirements.

On the other hand, maybe range does what you want? If it does, then a SortedMap might well provide a logN performance with smaller constant factor. Maybe.

Upvotes: 1

Rex Kerr
Rex Kerr

Reputation: 167901

The answer depends somewhat on how far apart x and y are, but you are generally best off using plain arrays. If you don't need to do anything with the slices, using views might be faster, but access is slower with views, so it's probably better to stay away from them.

Anyway, you certainly want something with fast "apply" (log or constant time), and between Array, Vector, and ArrayBuffer, Array is the fastest, ArrayBuffer is about 50% slower, and Vector is about twice as slow again for slicing and using every element that you've sliced.

Also, consider whether sliding will do what you want. It's not as fast as the direct slicing, but it's awfully convenient.

Upvotes: 1

Related Questions